Conventionally, as a method for determining a cylinder of an engine, it is known to provide a protrusion for cylinder identification in each of two rotating members that rotate in synchronization with a crankshaft and a camshaft and to detect a rotation angle position of an engine from a signal generated by a detecting element provided in the vicinity of the locus of the protrusion of each of the two rotating members (i.e., see Japanese Laid-Open Patent Publication No. H01-203656).
In four-cycle engines, a cycle of four processes of intake, compression, expansion and exhaust is completed with two rotations of a crankshaft, and therefore the reference cylinder cannot be determined without two rotations of the crankshaft. Therefore, when cylinder identification is performed with only the protrusion provided in the rotating member that rotates in synchronization with the crankshaft, that is, a crankshaft synchronization rotating member, for example, in a six-cylinder engine, it can be determined that the cylinder of interest is either one of the first cylinder and the fourth cylinder, but it cannot be determined precisely whether the cylinder of interest is the first cylinder or the fourth cylinder.
For this reason, as the above-described example, only with the position and the structure of the protrusions for cylinder identification and detection or rotation angle position detection provided in the crankshaft synchronization rotating member and the camshaft synchronization rotating member that rotates in synchronization with the crankshaft and the camshaft, proper cylinder identification cannot be performed, if signals generated by either one of a first detecting element and a second detecting element provided in the crankshaft synchronization rotating member and the camshaft synchronization rotating member are abnormal. Furthermore, the crank angle in each cylinder cannot be identified precisely, either.
The present invention is carried out in view of the above problem, and the object of the present invention is to provide a device for identifying a crank angle of an engine that allows proper cylinder identification of a four-cycle engine having a plurality of cylinders and precise identification of the crank angle in each cylinder.